CA1107805A - Variable magnification copying apparatus - Google Patents

Variable magnification copying apparatus

Info

Publication number
CA1107805A
CA1107805A CA268,031A CA268031A CA1107805A CA 1107805 A CA1107805 A CA 1107805A CA 268031 A CA268031 A CA 268031A CA 1107805 A CA1107805 A CA 1107805A
Authority
CA
Canada
Prior art keywords
optical
image
original
copy sheet
predetermined
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
CA268,031A
Other languages
French (fr)
Inventor
Koichi Miyamoto
Yoshikuni Tohyama
Seiji Sagara
Masato Ishida
Yoshimasa Kimura
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Canon Inc
Original Assignee
Canon Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to JP151411/1975 priority Critical
Priority to JP50151411A priority patent/JPS5911905B2/ja
Application filed by Canon Inc filed Critical Canon Inc
Application granted granted Critical
Publication of CA1107805A publication Critical patent/CA1107805A/en
Expired legal-status Critical Current

Links

Classifications

    • GPHYSICS
    • G03PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03GELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00Apparatus for electrographic processes using a charge pattern
    • G03G15/04Apparatus for electrographic processes using a charge pattern for exposing, i.e. imagewise exposure by optically projecting the original image on a photoconductive recording material
    • G03G15/041Apparatus for electrographic processes using a charge pattern for exposing, i.e. imagewise exposure by optically projecting the original image on a photoconductive recording material with variable magnification
    • GPHYSICS
    • G03PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03GELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00Apparatus for electrographic processes using a charge pattern
    • G03G15/22Apparatus for electrographic processes using a charge pattern involving the combination of more than one step according to groups G03G13/02 - G03G13/20
    • G03G15/28Apparatus for electrographic processes using a charge pattern involving the combination of more than one step according to groups G03G13/02 - G03G13/20 in which projection is obtained by line scanning
    • G03G15/30Apparatus for electrographic processes using a charge pattern involving the combination of more than one step according to groups G03G13/02 - G03G13/20 in which projection is obtained by line scanning in which projection is formed on a drum

Abstract

ABSTRACT OF THE DISCLOSURE
A variable magnification copying apparatus includes optical scanning means for scanning an image original at a variable velocity in accordance with a copying magnification desired, a photosensitive drum movable at a predetermined velocity from an exposure station to an image transfer station, conveyor means for conveying copy medium to the image transfer station, detector means for generating a signal when the scanning means has scanned an edge of the image original or a portion thereof near the edge, and control means coupled to the detector means for controlling the conveyor means by the signal so as to ensure that the image of the original to be copied is positioned with its leading edge registered with the leading edge of the copy medium with respect to the direction of conveyance, irrespective of changes in magnification.

Description

~1~78~5 BACKGROUND OF THE INVENTION

a Field of the Invention This invention relates to a variable magnification copying apparatus of the slit exposure type in which variable magnification copying is effected with a copy medium maintained at a predetermined velocity but with the velocity of optical scanning means varied.
bo Description of the Prior Art In order to obtain two or more steps of copy magnification in a variable magnification copying apparatus of the slit exposure type, there usually is adopted a method of changing the velocity of the optical scanning means while maintaining the copy medium at a predetermined velocityO According to this method,variable magnification copying can easily be accomplished by using entirely the same factors as those for the lx magnification copying in the processes such as charging and development of the photosensitive medium and in all the driving and conveying mechanisms other than the optical system. The scanning of an image original by the optical system usually is carried out in two alternative ways, one of which uses a movable optical system in which an illumination system, mirrors and the like are movable, and the other uses an original carriage movable with respect to the optical systemO
However, the optical scanning means mentioned herein means one of the optical system and the original carriage which is movable.
Usually, optical scanning means must be moved at a constant velocity as long as it optically scans an image original in the form of a slito Therefore, a suitable preliminary running range is provided on the way to one edge of the image original so that before the optical scanning means illuminates said one edge of the image original, the optical scanning means may assume a constant velocity '~' ~7~
and a light source for illumination may assume its steady state conditionO
Where variable magnification copying is effected by using the above-described method and, for example, if the velocity of a copy medium is V, the velocity of the optical scanning means during the lx magnification copying is of course equal to V, but the velocity of the scanning means during a Nx magnification copying is V/No Consequently, the time required for the optical scanning means to scan over the aforementioned preliminary running range differs from that required for the lx magnification copyingO
Thus, if copying is effected with the velocity of the optical scanning means alone varied but with the other conditions ; maintained identical to those for the lx magnification copying, the copy image formed on the copy medium may lack a portion cor-responding to the one edge of the image original or, conversely, a large blank or unimaged area will exist on the copy medium be-fore the one edge of the image original is copied, and this will sometimes result in an inconvenience that the other edge portion of the image original is left uncopiedO
To correct the misregistration between the image original and the copy medium resulting from such change in magnification during the variable magnification copying, the following methods come to mindO
(1) With respect to the copy medium effecting a pre-determined movement, the timing for starting the scanning of the optical scanning means is changed in accordance with ~ch magnifi-cation desired;

(2) With respect to the copy medium effecting a pre-determined movement, the preliminary running range for the optical scanning means is varied;

(3) With respect to the optical scanning means effecting a predetermined movement, the timing for starting the scanning of the copy medium is changed in accordance with each magnifi-cation desired;

(4) To detect the position of the copy medium and control the timing for starting the scanning of the optical scanning means; and

(5) To change the position of the image original on the ~ 10 original carriage in accordance with each magnification desiredO
However, the method mentioned under item (1) above would require a number of timers corresponding to the steps of magni-fication to be provided for controlling the optical scanning : means, and these timers would have to be adjusted for each magni-fication desired.
Also, since the optical scanning means has a certain degree of mass, there would be created a time loss from when the optical scanning means is subjected to a drive until it assumes a con-stant velocity of movement, namely, till the rising of the scann-ing meansO Where the drive means is a motor or the like, thetime loss would be varied by the state of the power source, temperature and frequency of use, and where the drive means is a magnet clutch or the like, the time loss would be varied by the state of the power source and the frequency of use, and it would be nearly impossible to achieve the aforementioned adust-ment in the cases including theseO
Further, in order to prevent the home position, namely, the preliminary running range, of the scanning means from being varied for each scanning cycle, a mechanism would be required 78~5 for holding the scanning means at its home position with high accuracy.
The method mentioned under item (2) above would involve, in addition to the above-noted problems, the necessity of pro-viding a complicated mechanism for driving the scanning means to a predetermined position before it starts scanning each time the copying magnification is changedO
The method mentioned under item (3) above would suffer from the drawbacks similar to those noted with respect to the item (l)o The method (4) is almost similar to the method (1) and in-stead of the timers, a number of copy medium detecting means corresponding to the steps of copy magnification would have to be adjusted.
The method (5) would require the operator of the apparatus to change the position of the image original in accordance with each magnification desired, and this would most undesirably lead to complicated manipulation and accordingly to malfunctioning of the apparatusO
SUMMARY OF T~E INVE~TION
It is therefore an object of the present invention to pro-vide a variable magnification copying apparatus which eliminates the above-noted inconveniencesO
It is another object of the present invention to provide such an apparatus which can perform copying with the timing for starting the scanning of the scanning means maintained constant irrespective of changes in copy magnification.
It is still another object of the present invention to provide such an apparatus which can perform copying with the preliminary running range of the scanning means maintained con-~tant irres~ective of changes in copy magnification.
It is yet still another object of the present invention to provide such an apparatus which can perform copying with the timing for starting the movement of copy medium with respect to the scanning means maintained constant irrespective of changes in copy magnification.
It is a further object of the present invention to provide such an apparatus which can perform copying by detecting the position of copy medium but without controlling the starting of the scanning of the scanning means.
It is a further object of the present invention to provide such an apparatus which can perform copying without changing the position of an image original placed on an original carriage.
It is a further object of the present invention to provide such an apparatus which can perform copying with the factors such as the position of the image original on the original carriage, the preliminary running range and the timing for starting the scanning of the scanning means, and the timing for starting the movement of copy medium being all maintained identical to those for the lx magnification copying even if the velocity of The present invention provides a variable magnification copying apparatus, comprising:
(a) optical means for forming an optical image of an original to be copied, said optical means including a displaceable optical element for changing the magnification of the optical image, (b) means for causing relative movement between the original and the optical means so that said optical means scans said original, the relative movement being at a speed which is changeable in accordance with the magnification selected to change the speed of scanning the original, (c) conveying means for moving a copy sheet from a pre- -determined position to an image forming station at a constant speed irrespective of the selected magnification, ~ 5 -~ ,,;

;7~ ' ~

(d) image formlng means for forming on said copy sheet at said station a second image corresponding to said optical image, (e) detecting means for producing a signal when a relative positional relationship between a leading edge of the original and optical means is reached, by said relative movement causing means, which relationship is independent of the selected magnification, and (f) control means for controlling said conveying means in response to said signal to move the copy sheet so as to provide a predetermined relationship between the leading edge of the copy sheet and the leading edge of the second image.
The invention will become more fully apparent from the following detailed description of some embodiments thereof taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
_ Figure 1 generally shows the construction of an embodiment of the variable magnification copying apparatus according to the present invention;
Figure 2 particularly shows the mechanism for conveying - Sa -~1~37~

copy medium in Figure l;
Figure 3 particularly shows the optical system in Figure l;
Figures 4 to 8 show the constructions of essential portions of further embodiments of the present invention;
Figure 9 is a block diagram of an embodiment of the drive control circuit;
Figure 10 is a block diagram of another embodiment of the drive control circuitO
DESCRIPTION OF THE PREFERRED EMBODIMENTS

.
Referring to Figure 1, there is shown an embodiment of the variable magnification copying apparatus accordin~ to the present invention which includes an apparatus housing lj an original carriage 2 formed by a transparent glass plate dis-posed on top of the housing 1, a first movable mirror 20, a second movable mirror 21, and a tubular light source 22 and a reflector 23 which are integrally mounted with the first movable mirror 200 The first movable mirror 20, with the light source 22 and the reflector 23, is moved in the direction of arrow a in parallelism to the original carriage 2, and the second movable mirror 21 is moved in the same direction as the first movable mirror 20 but at half the velocity of movement of the first movable mirror 200 The first movable mirror 20 and the second movable mirror 21 together constitute optical scanning meansO
The scanning velocity of this optical scanning means is variable in accordance with a desired copy magnification.
The apparatus further includes a transmission type lens 24 disposed ahead in the path of reflected light from the second movable mirror 21, a third mirror 25, a fourth mirror 26 and an exposure slit 270 The lens 24, the third mirror 25 and 37~

the fourth mirror 26 together constitute part of a magnifi-cation changing means, and these are displaceable to their re-spective broken-line positions in accordance with a desired copy magnification. When the desired copy magnification is lx, the lens 24, the third mirror 25 and the fourth mirror 26 are located at solid-line positions Ll, M3 and M4, respectivelyO
There is further seen a photosensitive drum 5 rotatable at a predetermined velocity in the direction of arrow b, a station 6 whereat the drum 5 is exposed to image light, a charger 7, a developing device 8 containing toner therein, a corona discharger 9 for expediting image transfer, an image transfer station 10 whereat the photosensitive drum 5 is con-tacted by copying paper P, and a cleaning mechanism ll~o The apparatus is further provided with paper rests (paper supply tables) 111 and 112 mounted in the lower portion of one side of the apparatus housing 1, paper feed rollers 121J 122, a first set of timing rollers 13, a set of intermediate transport rollers 14 and a second set of timing rollers 15D The rests 111 and 112 are loaded with sheets of copying paper (transfer medium) P of different sizesO The paper feed rollers 121 and 122 are coupled to a drive source (not shown) and as shown in Figure 2, they are respectively displaceable by electromagnetic plungers PLl and PL2 to a position in which they contact the copying paper on the respective paper rests and to a position in which they do not contact the copying paper (the position shown in Figure 2)o One of the electromagnetic plungers is operable in accordance with a copy size selectedO
Referring to Figure 2, the first set of timing rollers 13 and the intermediate transport rollers 14 are coupled to a 8~5 drive source M (motor) through a first clutch mechanism Cl, and the second set of timing rollers 15 is coupled to the drive source (motor) through a second clutch mechanism C2O The paper feed rollers 121, 122J the first set of timing rollers 13, the intermediate transport rollers 14 and the second set of timing rollers 15 together constitute copying paper conveying means which conveys copying paper at a velocity equal to the velocity of movement of the photosensitive drum 5O The apparatus further includes a copying paper separating mechanism 16, a heat-fixing device 17 and a tray 18 for receiving copying paper P having a copy image formed thereonO
In the copying apparatus of Figure 1, the image of an image original 0 illuminated by the light source 22 is scanned by the first movable mirror 20 and the second movable mirror 21 and is directed through the lens 24 and via the mirrors 25J 26 to pass through the slit 27 to the photosensitive drum 5 uniformly pre-charged by the charger 79 thus accomplishing the exposureO The original 0 is placed on the original carriage with one edge of the original registered to the reference position 3 on the carriage so that the starting end A of the scanning stroke for the original may always lie at a predetermined positionO The latent image formed on the photosensitive drum 5 SO exposed is developed by the developing device 8, whereafter the developed image is transferred to copying paper P by the corona discharge 9 at the image transfer station 10.
The paper rests 111 and 112 each loaded with a stock of copying paper are installed in two stages and copying paper may be supplied from either of these rests, as desiredO The paper paths from the two rests 111, 112 to the image transfer 37~

station 10 are merged into a single path at an intermediate point, and the lengths of these two paths are substantially equal to each otherO The paper feed rollers 121, 122 forming part of the copying paper conveying mechanism normally are rotated in their respective positions where they do not contact the stocks of copying paper, and in response to a paper feed signal, one of these paper feed rollers is lowered into contact with the uppermost sheet of the paper stock on an associated one of the paper rests, thus feeding a sheet of copying paperO The copying paper P so fed passes be-tween the first pair of timing rollers 13 located just downstreamof the paper rest for preventing oblique movement of the copying paper and for correcting the attitude thereof, which timing rollers are designed such that they temporally stop rotating and block the forward movement of the fed copying paper to thereby create a slack in the copying paper and thereafter, resumerotationO
On the other hand, the paper feed roller 121 (122) is again lifted out of contact with the stock of copying paper at a predetermined time after it was lowered, whereafter the conveyance of the paper is carried out by the first timing rollers and by subsequent paper conveying meansO
The copying paper conveyed by the first timing rollers 13 advances along the paper path and through the intermediate trans-port rollers 14 disposed at the junction of the two paper paths from the upper and lower paper rests, whereafter the paper is stopped at a predetermined position D for a reason which later will be describedO That is, the first timing rollers 13 and the intermediate transport rollers 14 are stopped from rotatingO
The first movable mirror 20 and the second movable mirror 21 forming the optical scanning means start scanning from their _ g _ home positions M10 and M20 (indicated by broken lines) in Figure 1 and before these movable mirrors 20 and 21 reach their second positions Mll and M21 (indicated by solid lines) and thus complete the scanning over the preliminary running range ~0 which precedes the position for scanning the edge A of the original, the single sheet of copying paper P fed from the rest 111 (112) has reached its set position D as already notedO When the optical scanning means reaches the edge A of the original, a cam 30 mounted on the first movable mirror 20 as shown in Figure 3 actuates a micro-switch MSo to generate a signal by which the first timing rollers 13 and the intermediate transport rollers 14 are restarted to convey the copying paper P which has been temporally stopped. A
series of these operations is accomplished by the first clutch mechanism Cl provided on the shaft for transmitting the drive to the first timing rollers 13 and to the intermediate transport rollers 14, and by electromagnetic plungers PLl and PL2 provided on a member for vertically moving the paper feed rollers 121, 122, and the control of these operations is accomplished by a timer which will later be describedO The lengths of the paper paths from the respective paper rests 111 and 112 to the image transfer station 10 are set to equal values, so that irrespective of the upward or downward movement of the rest, the copying paper can be stopped accurately at the predetermined position under the control of the timerO
The restarted copying paper P passes between the second timing rollers 15 disposed short of the image transfer station 10, and then reaches the image transfer station 10, where the copying paper is brought into intimate contact with the image on the photosensitive drum developed in the manner already described, ~1~7~
so that the image is transferred :Erom the photosensitive drumto the copying paper P0 After completion of the image transfer, the copying paper is separated from the photosensitive drum by the separating mechanism 16 and is conveyed to the heat-fixing device 17 for fixation of the image on the copying paper, where-after the copying paper is discharged onto the tray 180 During these steps of the process, the optical scanning means completes the scanning of the predetermined scanning section with the first and second mirrors 20 and 21 having reached their respective reverting positions M12 and M22 (indicated by broken lines) to start reversionO Simultaneously with the re-version, a feed signal for copying paper for the next copying cycle is generated by the optical scanning means, whereby the above-described sequence of steps from the paper feed to the paper conveyance is repeatedO When the optical scanning means comes back to its home position M10, M20, it again starts to scan the image originalO
Where multiple copies are desired, the above-described sequence of steps is repeated in accordance with the number of copies desiredO
In the above-described copying apparatus, copying at two steps of reduced magnification can be achieved in addition to the copying at the lx magnificationO If the copying ratio is selected to 1 : l/n : l/m, the scanning velocity of the optical scanning means is Vl : Vn (=nVl) : Vm (=mVl), where Vl is the scanning velocity for the copying at the lx magnification. More-over, in accordance therewith, the lens 24, the third mirror 25 and the fourth mirror 26 are movable to their respective posi-tions Ln, Lm, M3n, M3m, M4n, M4m, by a special mechanism (not 8~S

shown)0 When copying is to be effected at each of said magnifi- !
cations, the times Tl~?, Tn~ and Tm e required for the optical scanning means to scan over itq preliminary running range,~0 are set so as to satisfy the relation that Tl~ ~ T ~ ~Tm ~ Te' where Te is the time required for the illuminating light source to assume its steady state conditionO
The invention will now be explained with respect to the apparatus constructed as described aboveO Assume that the optical scanning means has started scanning from its home position M10, M20 at any of the abovementioned three velocities Vl, Vn (=nVl) and Vm (=mVl)0 Let a point B represent the point on the photo-sensitive drum whereat the edge A of the image original is imaged on the drum at a point of time whereat the optical scanning means having passed through the preliminary running range.~0 has scanned the edge A of the image original. When the point B on the photosensitive drum rotated at the predetermined peripheral velocity Vl has reached a point C corresponding to the image transfer station 10, and if the leading edge of the copying paper P conveyed by the conveyor means reaches the image transfer station 10, then the regiqtration between the leading edge of the copying paper and the leading edge of the copy image on the drum will be establishedO For various reasons, copying paper usually is conveyed at a velocity equal to the peripheral velocity Vl of the photosensitive drumO Therefore, if, at the point of time whereat the optical scanning means scans the edge A of the image original, the leading edge of the copying paper lies at the set point D which is retrogressive from the image transfer station by a distance corresponding to the distance ~Bc between the points ~1~78~5 B and C on the periphery of the photosensitive drum and if the copying paper is conveyed at the velocity Vl, then the leading edge of the copying paper and the leading edge of the copy image on the drum will register with each other at the image transfer station lOo Consequently, if the copying paper fed on from the paper rest is temporally stopped at the set point D in advance and if a signal is generated when the optical scanning means has scanned the edge A of the image original, to thereby restart the temporally stopped copying paper by the signal, then the regist-ration between the leading edge of the copy image and the leading edge of the copying paper may easily and perfectly be realized irrespective of any scanning velocity of the optical scanning meansO
Figure 9 shows, in block diagram, the drive control circuit for the copying paper conveying meansO In this Figure, reference character 40 designates a first timer, 41 a delay circuit, 42 a second timer and 43 a third timerO
A paper feed signal is supplied to a terminal 45. This paper feed signal is generated, for example, by the cam 30 on the first mirror 20 actuating the microswitch MS4 when the optical scanning means has reached its reverting position M12, M220 How-ever, this is not the only possible way to generate the paper feed signal but various other methods may be used to ~nerate such signalO When the paper feed signal is supplied to the terminal 45 upon closing of the microswitch MS4, the first timer 40 and the delay circuit 41 are operatedO Upon operation of the first timer 40, the electromagnetic plunger PLl (PL2) is energized to lower the paper feed roller 121 (122) onto the stock of copying ~78~i paper, thus feeding a sheet of copying paper P from the paper rest 11~ 2)o When the forward movement of the leading edge of the copying paper is blocked by the first timing rollers 13 so that the copy-ing paper becomes warped in its path, the second timer 42 is operated by the delay circuit 410 Upon operation of the second timer 42, the drive is transmitted through the first clutch mechanism Cl to the first timing rollers 13 and the intermediate transport rollers 14, so that the copying paper has its attitude corrected by the first timing rollers 13 and is conveyed therebyO
As soon as the copying paper P has been nipped between the first pair of timing rollers 13, the first timer 40 becomes inoperativeO
When the leading edge of the copying paper P reaches the set position D, the second timer 42 becomes inoperative and the copy-ing paper is stopped. Subsequently, the optical scanning means starts scanning and reaches the edge A of the image original, whereupon the cam 30 on the first mirror 20 closes the microswitch MSo to thereby operate the third timer 430 Upon operation of the third timer 43, the drive is transmitted through the first clutch mechanism Cl and the second clutch C2 to the first timing rollers 13, the intermediate transport rollers 14 and the second timing rollers 15, whereby the copying paper is again conveyedO
Since, as already noted, the distance of movement ~BC f the photosensitive drum between the exposure station 6 and the image transfer station 10 is equal to the distance of movement of the copying paper between the set position D and the image transfer station 10, the leading edge of the copy image formed on the photosensitive drum and the leading edge of the copying paper P
are registered to each other at the image transfer station 10 8~

irrespective of the change in the scanning velocity, therebyensuring a proper copy image to be formed on the copying paper PO
In Figures 1 and 2, the two paper paths from the two paper rests 111, 112 to the image transfer station 10 are ~ual to each other but longer than the distance ~BC between the points B and C on the periphery of the photosensitive drum, whereas this is not restrictive but, as shown in Figure 4, the paper rests 11 may be disposed at a position corresponding to the set position D in the paper path, namely, such a position that the entire length of the paper path is equal to the aforementioned distance ~ BC As a further alternative, the entire length of the paper path may be shorter than said distance ~BC' as shown in Figure 5.
In the case of Figure 4, the feeding of copying paper P from the paper rest 11 may be started at the point of time whereat the optical scanning means ha-~ scanned the edge A of the image originalO
In the case of Figure 5, the feeding of copying paper P from the paper rest 11 may be started with a time delay t = (~BC -~p)/Vl provided by the timer with respect to the signal generated when the optical scanning means has scanned the edge A of the image original, said time delay t being the time required for the copy-ing paper to pass at the predetermined velocity Vl through a path corresponding to the difference (~BC ~ ~p) between the entire length.~p of the aforementioned paper path (~p - eBC~ and the aforementioned distance ~BC
Further, where a plurality of copying paper rests are in-stalled, the lengths of the paper paths from the respective paper rests to the image transfer station 10 need not always be equal to one another as shown in the embodiment of Figures 1 and 2J
but, for example, the lengths of the paper paths from the paper - 15 ~

~78~'S

rests 111, 112, 113 to the image transfer station may differ from one another to obtain the same operational effect as that obtained by the embodiment of Figures 1 and 2, provided that the distance CD between the temporary stop position or the set position D
of the copying paper from each of the paper rests and the image transfer station is made equal to the aforementioned distance ~-Bc on the photosensitive drumO
In the embodiment of Figure 6, a micromotion micro-switch MS as the means for temporally stopping the copying paper at the set position D is installed at the set position D in the paper path to detect the leading edge of the copying paperO
Figure 10 is a block diagram of the drive control circuit for the copying apparatus of Figure 60 In this Figure, the ele-ments identical to those in Figure 9 are designated by identical reference characters. In Figure 10, the reference numeral 50 de-notes a change-over circuit which may comprise a flip-flop, for example~
When a paper feed signal is supplied from the terminal 45, the electromagnetic plunger PLl (PL2, PL3) is energized by the first timer 40 to feed a sheet of copying paper P0 When a signal is supplied from the delay circuit 41, the changer-over circuit 50 is changed over to operate the first and second clutch mecha-nisms Cl and C2 to convey the copying paper P0 As soon as the leading edge of the copying paper P is detected by the micro-switch MS, the change-over circuit 50 is changed over to render the first and second clutch mechanisms inoperative, thus stopping the copying paper P. Subsequently, the microswitch MSo is closed, whereupon the change-overcircuit 50 is again changed over to operate the first and second clutch mechanisms Cl and C2, whereby the copying paper P is again conveyedO
The means for temporally stopping the copying paper is not restricted to the shown example but may be the detection method using ultrasonic wave or the detection method using both a light emitting element and a light receiving elementO As a further alternative, a timer may be used for each of the paper rests so as to vary the distance over which the copying paper is initially fed from each paper rest to the aforementioned set position D.
Of course, any of these methods is equally applicable in the other embodiments.
In the above-described embodiment, either detector means using a micromotion microswitch or the like for detecting the position of the copying paper or a timer set so as to feed the copying paper by a predetermined distance from the paper rest is used to temporally stop the copying paper at the set position Do However, for example, where a microswitch or the like is employed in the path of copying paper, the stop position of the copying paper may be varied by the self-supporting strength of the copying paper itself, and even where a timer or the like is employed, the operation of the timer may not always be.uniform every time and second registration means will have to be provided if it is desired to provide a more accurate registrationO
Figure 7 shows an embodiment in which a second set of timing rollers is disposed at a location in the paper path as near as possible to the image transfer stationO
The second timing rollers 15 are functionally similar to the first timing rollers 130 That is, the second timing rollers are designed to temporally stop rotating a moment before the arrival of copying paper to thereby block the forward movement of 7~

the leading edge of the copying paper and create a slack in thecopying paper, and thereafter resume rotation, thus eliminating the problem noted above, and the second timing rollers have the function of performing the final delicate registration immediate-ly before the image transfer station.
The signal for controlling the second timing rollers 15 may be produced, for example, by the optical scanning means in the manner as shown in Figure 30 In this case, the second timing rollers may be designed such that they stop rotating as long as the cam 30 attached to the first mirror 20 of the optical scanning means scans over the microswitch MSl, MS2 or MS3 in accordance with the copying magnification desiredO
As an alternative, where the distance ~BC between the points B and C on the photosensitive drum is relatively short as shown in Figure 8, the second timing rollers 15 may be installed at the aforementioned set position D which is at a distance from the image transfer station 10 equal to the aforementioned distance BC- whereby registration may be achieved with a relatively high accuracyO
According to the present invention, as has hitherto been described, registration between the leading edge of the copy image and the leading edge of the copying paper can be achieved simply by detecting the point of time whereat the optical scann-ing means scans the edge of the image original~ irrespective of the number of the position of the copying paper rests and irres-pective of any scanning velocity of the optical scanning means.
Moreover, the present invention can perform a reliable and stable function without being affected by the unstabilizing factors in the rising portion of the stroke of the optical scanning meansO

~7~S
Although the mirrors 20 and 21 forming the optical scann-ing means have been shown as movable, these mirrors may be made stationary while the original carriage may be constructed as movable to scan at a velocity in accordance with a desired magnification.

Claims (17)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A variable magnification copying apparatus, comprising:
(a) optical means for forming an optical image of an original to be copied, said optical means including a displaceable optical element for changing the magnification of the optical image, (b) means for causing relative movement between the original and the optical means so that said optical means scans said original, the relative movement being at a speed which is changeable in accordance with the magnification selected to change the speed of scanning the original, (c) conveying means for moving a copy sheet from a predetermined position to an image forming station at a constant speed irrespective of the selected magnification, (d) image forming means for forming on said copy sheet at said station a second image corresponding to said optical image, (e) detecting means for producing a signal when a relative positional relationship between a leading edge of the original and optical means is reached, by said relative movement causing means, which relationship is independent of the selected magnification, and (f) control means for controlling said conveying means in response to said signal to move the copy sheet so as to provide a predetermined relationship between the leading edge of the copy sheet and the leading edge of the second image.
2. An apparatus according to claim 1, including a support table having an index for registering the leading edge of the original, the detecting means including one part fixed relative to said index and one part fixed relative to the optical means, one of the parts comprising a sensor and the other part comprising an actuator for the sensor such that on relative movement during scanning the sensor will be actuated when the predetermined relative positional relationship has been reached between the leading edge of the original and the optical means.
3. An apparatus according to claim 2, in which the support table for the original is movable relative to stationary optical means to scan the original, the speed of the table being variable in accordance with the selected magnification.
4. An apparatus according to claim 2, in which the optical means includes a movable part which is movable relative to the stationary support table to scan the original, the speed of the movable part being variable in accordance with the selected magnification.
5. An apparatus according to claim 4, in which the optical means includes first and second reflecting means movable in the same direction with the first reflecting means moving at twice the speed of the second.
6. An apparatus according to claim 4, in which said detecting means includes a part which is fixed relative to the movable part of said optical means.
7. An apparatus according to claim 2, 3, or 4, in which the detecting means produces the signal when the optical means scans the leading edge of the original, or a region in the vicinity of the edge.
8. An apparatus according to claim 5 or 6, in which the detecting means produces the signal when the optical means scans the leading edge of the original, or a region in the vicinity of the edge.
9. An apparatus according to claim 1, comprising an electrophotographic photosensitive member traveling, at said constant speed irrespective of the selected magnification, along a predetermined path sequentially through an exposure sta-tion at which the optical image is exposed on the photo-sensitive member, and through the image forming station to transfer the second image to the copy sheet.
10. An apparatus according to Claim 1, comprising storage means for storing the copy sheet, and supplying means for supplying the copy sheet from the storage means to said predetermined position.
11. An apparatus according to Claim 10, in which the supplying means supplies the copy sheet, before the signal actuates the conveying means, from the storage means to the predetermined position.
12. An apparatus according to Claim 10 or 11, in which a copy sheet detector is provided for producing a signal to render the supplying means inoperative when the copy sheet reaches the predetermined position.
13. An apparatus according to Claim 1, in which the detecting means produces the signal when the optical means scans the leading edge of the original, or a region in the vicinity of the edge.
14. An apparatus according to Claim 13, in which the conveying means starts to move the copy sheet from the predetermined position substantially simultaneously with generation of the signal.
15. An apparatus according to Claim 14, comprising an electrophotographic photosensitive member travelling, at said constant speed irrespective of the selected magnifica-tion, along a predetermined path sequentially through an exposure station at which the optical image is exposed on the photosensitive member, and through the image forming station to transfer the second image to the copy sheet, wherein the distance between the predetermined position and the image forming station is the same as the distance between the exposure station and the image forming station, the conveying means conveying copy sheet at the same speed as the photosensitive member.
16. An apparatus according to Claim 13, in which the control means includes a timer connected to the detec-ting means, said timer actuating the conveying means to move the copy sheet from the predetermined position a pre-determined time after reception of the signal.
17. An apparatus according to Claim 16, compri-sing an electrophotographic photosensitive member travel-ling, at said constant speed irrespective of the selected magnification, along a predetermined path sequentially through an exposure station at which the optical image is exposed on the photosensitive member, and through the image forming station to transfer the second image to the copy sheet, wherein the distance between the predetermined position and the image forming station is less than that of the exposure station and the image forming station, the conve-ying means conveying the copy sheet at the same speed as the photosensitive member, and the predetermined time cor-responding to the time required for the copy sheet to be conveyed over a distance corresponding to the difference between the length of the movement path of said photosensi-tive member from said exposure station to said image forming station and the length of the conveyance path of copy sheet from the predetermined position to the image forming station.
CA268,031A 1975-12-18 1976-12-16 Variable magnification copying apparatus Expired CA1107805A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
JP151411/1975 1975-12-18
JP50151411A JPS5911905B2 (en) 1975-12-18 1975-12-18

Publications (1)

Publication Number Publication Date
CA1107805A true CA1107805A (en) 1981-08-25

Family

ID=15518004

Family Applications (1)

Application Number Title Priority Date Filing Date
CA268,031A Expired CA1107805A (en) 1975-12-18 1976-12-16 Variable magnification copying apparatus

Country Status (7)

Country Link
US (1) US4129377A (en)
JP (1) JPS5911905B2 (en)
AU (1) AU507220B2 (en)
CA (1) CA1107805A (en)
DE (1) DE2657426C2 (en)
FR (1) FR2335869B1 (en)
GB (1) GB1576107A (en)

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Also Published As

Publication number Publication date
US4129377A (en) 1978-12-12
GB1576107A (en) 1980-10-01
JPS5275332A (en) 1977-06-24
FR2335869B1 (en) 1982-05-07
AU507220B2 (en) 1980-02-07
DE2657426A1 (en) 1977-06-30
AU2061976A (en) 1978-06-22
DE2657426C2 (en) 1986-06-19
FR2335869A1 (en) 1977-07-15
CA1107805A1 (en)
JPS5911905B2 (en) 1984-03-19

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